Surge suppression system for medium and high voltage

ABSTRACT

A system of surge suppressor units is connected at multiple locations on a power transmission and distribution grid to provide grid level protection against various disturbances before such disturbances can reach or affect facility level equipment. The surge suppressor units effectively prevent major voltage and current spikes from impacting the grid. In addition, the surge suppressor units include various integration features which provide diagnostic and remote reporting capabilities required by most utility operations. As such, the surge suppressor units protect grid level components from major events such as natural geomagnetic disturbances (solar flares), extreme electrical events (lightning) and human-generated events (EMPs) and cascading failures on the power grid.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/266,535, filed on Sep. 15, 2016, which is a continuation ofU.S. patent application Ser. No. 14/931,060, filed on Nov. 3, 2015 (nowU.S. Pat. No. 9,450,410), which is a continuation of InternationalApplication No. PCT/US2015/035305, filed on Jun. 11, 2015, which claimsbenefit of U.S. Provisional Patent Application No. 62/010,746, filed onJun. 11, 2014, the disclosures of all of which are incorporated hereinby reference in their entirety.

FIELD OF THE INVENTION

The invention relates to a surge suppression system for medium and highvoltage systems of a power grid.

BACKGROUND AND SUMMARY

Current surge suppression systems have been developed to protectequipment from voltage transients on one side of a three-phase powersupply bus used in industrial settings such as in plants, factories, orother large scale systems. In one known voltage surge suppressor, threesingle-phase transformers are provided with terminals that are eachconnected through a fused disconnect to a respective single-phase powersupply on the power-supply bus. This surge suppressor protects againstvoltage transients, which can severely damage or destroy equipmentconnected to the effected three phase circuit or can cause power outagesthroughout the plant. The surge suppressor circuit operates as a surgeand fault protector for any equipment on the power bus. This surgesuppressor system is usable with 480 volt distribution systems poweredby a 2000 to 3000 kVA ungrounded delta power transformer that feedsapproximately 1000 ft of bus duct, so as to generally have about 1 to 3Amperes of charge current. This charge current may generally be justover 2 Amperes by actual amperage determined by readings in the field,wherein the variations are due to the lengths of the feeder cable andbus duct as well as the number and size of the electric motors and powerfactor correction capacitors operating at any given time. Moretypically, resistance grounding circuits constantly bleed this charge toground to help prevent grounding problems. The known surge suppressor isconnected to the bus bars and does not bleed this energy to ground, butuses this charge energy to help stabilize and balance the phase voltagesto ground.

This known surge suppressor is installed in and protects equipmentconnected to a power supply bus at the facility level. However, there isa need for a surge suppressor system for medium and high voltageelectrical systems on the grid located outside of and remote from anindustrial bus bar power supply system.

A power grid is comprised of many components that are genericallydescribed as generators, transformers, transmission and distributionwires and controls. Generators are driven by many forms of energy suchas coal, natural gas, nuclear fission, hydro, solar and even wind toname a few. Once power is created at a relatively low voltage around6,000 volts it is stepped up to high voltage (often in the hundreds ofthousands) using large power transformers (LPTs) which allow theelectricity to be more effectively delivered over miles of high tension(transmission) wires. Once the electricity reaches the general areawhere it will be used it is then stepped back down closer to the finalvoltage at sub/distribution stations. Distribution lines carry near-lowvoltage electricity on roadside power poles or underground to the finaltransformer before being delivered into buildings for use.

The present invention is a surge suppressor system that improves uponexisting phase adder circuit products, is designed to provide grid-levelprotection to residences and industrial facilities prior to delivery ofthe power to these structures so they can withstand higher voltages,provide monitoring and communication from remote settings, and providemore robust installation platforms, and configures the system of surgeprotection devices in parallel to protect grid level applications onboth sides of a power system where the need exists to step power eitherup or down.

On a medium or high voltage system, the current invention would beconfigured to handle large and rapid energy “drain offs”, preventinterference from high voltage/high magnetic flux, allow remoteperformance maintenance, and increase protection, as required, fromphysical attacks and severe over voltages. When the invention isinstalled in parallel with critical grid infrastructure, the componentsof the grid are protected against:

Transients: An impulsive transient is what most people are referring towhen they say they have experienced a surge or a spike. Many differentterms, such as bump, glitch, power surge, and spike have been used todescribe impulsive transients. Causes of impulsive transients includelightning, poor grounding, the switching of inductive loads, utilityfault clearing, and Electrostatic Discharge (ESD). The results can rangefrom the loss (or corruption) of data to physical damage of equipment.Of these causes, lightning is probably the most damaging. The surgesuppressor devices of the current invention provide grid-levelprotection against such transients.

Interruptions: An interruption is defined as the complete loss of supplyvoltage or load current. The causes of interruptions can vary but areusually the result of some type of electrical supply grid damage, suchas lightning strikes, animals, trees, vehicle accidents, destructiveweather (high winds, heavy snow or ice on lines, etc.), equipmentfailure, or a basic circuit breaker tripping. While the utilityinfrastructure is designed to automatically compensate for many of theseproblems, it is not infallible.

Sag/Under-voltage: A sag is a reduction of AC voltage at a givenfrequency for the duration of 0.5 cycles to 1 minute's time. Sags areusually caused by system faults and are also often the result ofswitching on loads with heavy startup currents.

Swell/Over-voltage: A swell is the reverse form of a sag, having anincrease in AC voltage for a duration of 0.5 cycles to 1 minute's time.For swells, high-impedance neutral connections, sudden (especiallylarge) load reductions, and a single-phase fault on a three-phase systemare common sources.

Frequency Variations: There are all kinds of frequency issues fromoffsets, notching, harmonics, and inter-harmonics; but these are allconditions that occur largely in the end user's power system. Thesevariations happen because harmonics from loads are more likely insmaller wye type systems. The high frequency variations that may lead tomassive interconnected grid failure would come from the sun or enemyattack. Damage to only a few key infrastructure components could resultin prolonged blackouts and collateral damage to adjoining devices. Solarflares are natural occurrences that vary in severity and direction. This“solar weather” is sent out from the surface of the sun throughout oursolar system in all directions. These flares contain large amounts ofmagnetic energy and depending on how they hit the earth can causecomponent damage on the surface or by temporarily changing theproperties of the planet's magnetic core. Either way, a direct hit oflarge proportion could cause equipment failure and black out entireregions. Electromagnetic Pulses (EMP) can be used in similar fashion butdirected by enemy combatants in the form of a high altitude nuclearexplosion. A well-executed detonation over Cincinnati, Ohio could blackout 70% of the American population. Damage to large power transformersor generators could take months to repair. The high frequencydisturbance of nuclear explosions can destroy unprotected componentsmuch like an opera singer's voice can break a glass. The magnitude ofeach disturbance may depend on the source but each can be mitigatedeffectively through the use of a phased voltage stabilization systemsuch as the invention.

Current surge suppression technology may attempt to address thesedisturbances on the facility side of the power distribution system, soas to directly protect equipment in a facility, and also at a grid levelbut these technologies possess drawbacks in protecting against thesedisturbances.

As one example of a known surge suppression technology, capacitors arethin conductors separated by even thinner layers of insulation.Capacitors have a design rating for current and voltage. If this ratingis not exceeded they will typically operate for 10 to 15 years. One highvoltage spike may (and generally will) cause catastrophic failure ofcapacitors. In factories with 4,000 power factor correction capacitors,it is not uncommon to have 300 to 500 capacitors fail each year due tohigh harmonic current or high voltage spikes.

In another example, SPD (Surge Protective Devices) are solid statedevices constructed in various sizes. Like capacitors, their ratings arealso in current and voltage. When the MOV (Metal Oxide Varistor) is hitwith many low-level voltage spikes it degrades, and the “clampingvoltage” will rise as the MOV breaks down, allowing the clamping voltageto continue to rise until it no longer protects the equipment it wasinstalled to protect. When a voltage spike hits the MOV above the ratedvoltage, it starts to conduct thousands of amps to ground, causing noiseon the ground system and very high heat within the SPD. If the event islonger than a few millionths of a second, the MOV could be destroyed,and therefore would no longer protect the equipment it was installed toprotect.

Further, Faraday cages have been used for many years to house andprotect computer hardware and sensitive data in factories, as well assome government and military buildings. They recently have been toutedas a solution to solar flares, lightning and EMP pulse issues. However,most buildings are not built within a metal enclosure and it isdifficult and expensive to properly design and build these enclosures.Most automobiles, trucks, trains and planes are totally enclosed bymetal, but they offer no protection from any of these events. By design,the metal enclosure must have a suitable solid ground connection as itrelies heavily on enclosing and shielding the sensitive electricalequipment and removing the energy by draining it to ground. The powercompany uses the Faraday cage design in some of their grid tiesubstations. They are extremely large and expensive.

The greatest threat to the grid/LPTs is the presence of anelectromagnetic pulse (EMP) or geomagnetic disturbance (GMD), the latterwould originate as a solar flare and the prior would be from enemyweaponry. Either threat could cause an overworked LPT to be saturatedwith power and cause the transformer to burn out. With an EMP,saturation could happen in less than a second so detection systems areworthless.

GMD is slower to cause damage so detection systems could reduce the loadon a transformer which could allow it to ride out the GMD incident. Thisbrown out or temporarily blacked out condition could last minutes, hoursor days depending on the severity of the solar storm. In the case of the1869 Carrington Event the Earth was pummeled with solar magnetic energyfor nearly a month. While the grid could survive such an event ifproperly managed it would hardly be well received by citizenry to bewithout power that long.

Simply, Large Power Transformers cannot be protected with old technologylike Faraday Cages. The hundreds of miles of wire that connect the LPTto sub stations way down the line act like antennae and harvest EMP withsuch efficiency that the Faradays would have no value. Surge protectingdevices are not fast enough to arrest an EMP which occurs in a millionthof a second or handle the massive electron flow that occurs at thetransmission level without allowing current bleed through to the LPTwhich would ultimately have the same effect as an unprotected system.Grounding systems would try to route surplus current from an EMP toearthen ground probes or mats but that excess energy would likely findits way back into the power system through the ground bus and result inburnout as well.

The present invention relates to a system of surge suppressor unitsconnected at multiple locations on the grid to provide grid levelprotection against various disturbances before such disturbances canreach or affect facility level equipment. The effect of the invention issignificant for protecting grid level applications. With the uniqueapplication and design of the present application, the surge suppressorunits of the present invention would effectively prevent major voltageand current spikes from impacting the grid. In addition, the surgesuppressor units included various integration features which providediagnostic and remote reporting capabilities required by most utilityoperations. As such, the surge suppressor units protect the grid levelcomponents from major events such as natural geomagnetic disturbances(solar flares), extreme electrical events (lightning) andhuman-generated events (EMPs) and cascading failures on the power grid.The invention also provides significant protection against arc flashesand reduces voltage harmonics that exists in “normal” grid operations.

The reporting features of the inventive surge suppressor unit are alsounique to protecting medium and high voltage systems that are often inremote or isolated settings. Unlike devices designed to protect locallow voltage equipment and infrastructure, real time diagnostic reportingfrom the surge suppressor unit is critical to ensure it is workingeffectively and providing the continuous protection needed to protectpower systems like the US power grid.

As discussed, various known technologies (such as MOVs, Faraday cages,even similar devices designed with fused disconnects) attempt to alsocorrect voltage imbalances. These devices either do not provide thescalability to the voltage requirements at the grid level or “burn out”when significant voltage is applied. These technologies also do notprovide reporting, remote diagnostics, or protection from ancillarydangers such as arc flashes or localized voltage overflow. The surgesuppressor system of the present invention provides each of thesebenefits and is also completely scalable for various grid levelapplications.

Other objects and purposes of the invention, and variations thereof,will be apparent upon reading the following specification and inspectingthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagrammatic view of power grid interfaces with a system ofsurge suppressor units connected thereto at various locations on theelectrical supply grid.

FIG. 1B is an enlarged partial view of FIG. 1A showing the transmissiongrid.

FIG. 1C is an enlarged partial view of FIG. 1A showing the distributiongrid.

FIG. 2 illustrates typical fault conditions.

FIG. 3 diagrammatically illustrates a protection scenario (20) for gridlevel components (e.g. substations) at a grid level.

FIG. 4 illustrates a surge suppression unit (30) comprised ofshunt-connected three phase transformer banks that is referenced ascomplete units (21, 22, and 23) on FIG. 3.

FIG. 5 illustrates a remote monitoring system.

FIG. 6 is a graph showing test results of a surge suppressor unitinstalled on a three phase circuit when subjected to an E1 EMP pulsecomponent.

FIG. 7 is a graph showing test results of a surge suppressor unitinstalled on a three phase circuit when subjected to an E2 EMP pulsecomponent.

FIG. 8 is a graph showing test results of a surge suppressor unitinstalled on a three phase circuit when subjected to an E3 EMP pulsecomponent.

FIG. 9 is a graph showing test results of a surge suppressor unitinstalled on a three phase circuit when subjected to an E3 EMP pulsecomponent with the threat pulse removed.

Certain terminology will be used in the following description forconvenience and reference only, and will not be limiting. For example,the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” willrefer to directions in the drawings to which reference is made. Thewords “inwardly” and “outwardly” will refer to directions toward andaway from, respectively, the geometric center of the arrangement anddesignated parts thereof. Said terminology will include the wordsspecifically mentioned, derivatives thereof, and words of similarimport.

DETAILED DESCRIPTION

Referring to FIGS. 1A-1C, a generalized power distribution system 10 isshown which discloses various power system components at the grid levelwhich supply power to individual consumers at the facility level. Forpurposes of this disclosure, the facility level includes industrial andfactory facilities and the like, as well as residential facilities suchas homes and apartment buildings. These structures include various typesof power consuming devices or power consumers such as various types ofequipment, motors and appliances. Stand-alone power consuming devicesare also supplied by the power grid, such as street lighting, trafficsignals, and other power consumers.

More particularly, the power distribution system 10 includes atransmission grid 11 at high voltage levels and extra high voltagelevels, and a distribution grid 12 at medium voltage levels, which inturn supplies lower power at the facility level to residences, factoriesand the like. FIG. 1B shows various power supply sources which generatepower at extra high voltages such as a coal plant, nuclear plant and ahydro-electric plant. These may supply power through step-uptransformers 13 to an extra-high voltage transmission grid 14. This grid14 may in turn connect to a high voltage grid 15 through a network oftransformers 16, which grid 15 is connected to various grid facilitiessuch as an industrial power plant, factory, or a medium sized powerplant through respective networks of transformers 17. Generally, mediumvoltage refers to the range of 10 kV-25 kV or higher which is typicallycarried in the distribution grid and may include generation voltages,high voltage refers to the range of 132 kV-475 kV as might exist in thetransmission grid, and extra high voltage is in the range of 500 kV-800kV, which also is typically carried in the transmission grid. These gridlevel voltages are significantly higher than the low voltages presentwithin a facility or other similar structure.

The transmission grid 11 may in turn connect to a medium voltagedistribution grid 12 (FIG. 1C) through a network of transformers 18. Inturn the residential grid 12 may include various facilities such as citypower plants, industrial customers, solar farms, wind farms,agricultural farms, rural networks of residences or city residentialnetworks. Various transformers 18 are provided to interconnect thesecomponents of the power distribution system 10. Generally, the presentinvention relates to a surge suppressor system which is installed atvarious locations within the power distribution system 10 to providegrid level surge suppression and thereby protect the various facilitiessupplied with power from the power distribution system 10. These varioustransformers may be of various types and configurations such as step-upand step-down transformers, as well as substation transformers installedin substations or delivery transformers which serve to supply individualcustomers.

The invention relates to a system of voltage surge suppressor units 20that are installed at various locations on the power distribution grid10 to provide three-phase, grid level protection to various facilitieswhich receive power from or supply power to such grid 10. FIG. 3generally illustrates a system of multiple surge suppressor units 20which are differentiated from each other in FIG. 3 by reference numerals21, 22 and 23. These surge suppressor units 21, 22 and 23 are sized forthe particular installation location and the voltage levels presentwithin the power distribution system 10 at such locations. Generally,the power grid uses various transformers described above, with therepresentative grid transformer 24 of FIG. 3 being one of the varioustransformers used in the transmission grid 11 or distribution grid 12.The transformer 24 includes a primary side coil 24P which is connectedto three power lines 25A, 25B and 25C which supply power, for example,from a generation plant or the like to the grid transformer 24. Thetransformer 24 includes a secondary side coil 24S which connects totransmission lines 26A, 26B and 26C for supplying power to downstreamcomponents of the power grid. In this exemplary embodiment, thetransformer 24 steps up the power from 6 kV received from the generationside power lines 25A, 25B and 25C to 300 kV as supplied to the gridpower lines 26A, 26B and 26C. It will be understood that voltages forthe primary and secondary sides of the transformer 24 can vary dependingupon the location within the power grid, wherein the voltage levels canbe medium or high voltages.

The surge suppressor unit 21 connects to the generation power lines 25A,25B and 25C and the primary side coil 24P to protect against the varioustransient conditions described above which thereby protects the primarycoils 24P and the upstream power generators and any upstream gridcomponents and equipment. The surge suppressor unit 22 in turn connectsto the grid or transmission power lines 26A, 26B and 26C and thesecondary side coil 24S to protect against the various transientconditions described above which thereby protects the secondary coils24S as well as the downstream transmission lines 26A, 26B and 26C aswell as any connected grid equipment and components. Also, the surgesuppressor unit 23 may be a 480V unit or other suitable voltage levelsuitable to protect system circuitry and logic.

Referring to FIG. 4, each surge suppressor unit 21, 22 and 23 cangenerally use the design of the surge suppressor unit design 20 (FIG. 4)that comprises a series of shunt-connected three phase transformer banks31, 32 and 33 that are designed to correct phase neutral voltageimbalances by feeding them back onto themselves and/or draining theimbalances off to the integrated resistor bank that is wired to thesecondary side of the system as also shown in FIG. 4. Each transformerbank 31, 32 and 33 includes primary coils 31P, 32P and 33P which connectto and receive power from one of the power transmission lines L1, L2 andL3 of the system, which may be at the medium or high voltages present inthe power grid. The primary coils 31P, 32P and 33P also connect toground 34. The lines L1, L2 and L3 may for example be connected totransmission lines 26A, 26B, 26C (FIG. 3) and supplied by powergenerator and mega transformers shown in FIG. 4, or lines 25A, 25B, 25Cin the example of FIG. 3.

Each transformer bank 31, 32 and 33 also includes secondary coils 31S,32S and 33S which connect in series together and have a resistor 35connected in series therewith. The series connected resistor 35 providesboth noise filtering and a discharge path for energy during a power downwhether intentional or caused by a natural occurrence. The resistor 35also helps to drain system energy to prevent an arc-flash since an arcflash is a series phenomenon. By holding up the remaining phases duringa fault, voltage buildup cannot form and simply allows circuitprotection to open the circuit without a flashing event. This enhancedstability ensures cleaner electron flow and renders the flow safer forcomponents and personnel alike. In other words the surge protection unit30 balances the voltage on the “load” side. Since the flash isinherently on the “source” side, the voltage across the arc is minimaland the arc will be suppressed.

Each surge suppressor unit 20 utilizes a circuit breaker 36 governingpower from each of the lines L1, L2 and L3 that can be programmed torapidly reset and can be made scalable to medium and high voltagerequirements. The circuit breaker 36 also may be manually operated forinstallation and replacement of the surge suppressor unit 20, or anotherswitch device could be included to provide manual switching of the surgesuppressor unit 20. Depending of the requirements of the utilityorganization, added protection, in the form of Metal Oxide Varistors,can be series piped in as a secondary circuit as severe over voltageoccurs.

With this construction, the surge suppressor unit 20 thereby balancesphase voltages with respect to ground by pushing clean phase shiftedcurrent into the phase with the lowest phase voltage. The componentspreferably are matched single phase transformers 31, 32 and 33 and inthis permanent solution are sized to the voltage class and kVA in whichthe particular surge suppressor unit 20 will be employed. The voltagespecification determines the appropriate turn ratios needed to properlysize each surge suppressor unit 30 to its installation location. Allthree transformers 31, 32, and 33 are spaced from one another by IEEEstandards to prevent arcing or magnetic flux between each phase.Depending on the specific requirements, the surge suppressor units 20 ofthe invention may utilize underground installation with oil/coolantimmersed resistor banks 35 and oil cooled transformers 31, 32, 33. Theseoptions would allow for closer spacing (smaller footprint) and requireless mechanical or free air cooling. These options would also removeequipment from line of sight hostilities.

During installation, each surge suppressor unit 20 is wired in parallelto the power system, for example, as seen in FIG. 3. Further, a surgesuppressor unit 20 such as unit 22 in FIG. 3 may protect from thesecondary side 24S of a power transformer 24 to the primary side of thedownstream transformer to provide extended protection extending from thesurge suppressor units 20 to other power components connected thereto.For example, a surge suppressor unit 20 may protect from the secondaryside of an LPT down to the primary windings of the next step downtransformer. Additional surge suppressor units 20 would be installed onthe next portion of the stepped down power system beginning with thesecondary of that distribution transformer down to the primary on thenext transformer and so on. Each surge suppressor unit 20 would beengineered and constructed to operate with the hookup voltage and the VArating of the transformer it is designed to protect, such that differentsized and rated surge suppressor units 20 would be installed in thepower grid depending upon the location of installation. This extendedprotection is also true from the generation source to the primary side24P on the initial transformer 24 which is protected by the surgesuppressor unit 21 in FIG. 3. All connected components would beprotected, and the surge suppressor unit 20 of the present inventionwould stabilize imbalances whether caused by downstream activity ordirectly on line.

Further, no power system would need to be turned off to connect thesurge suppressor units 20. The circuit breaker 36 or other suitabledisconnect device 36A can be manually operated such that utility linemencould hot tap the surge suppressor devices 20 into the system and thenengage each surge suppressor unit 30 by using the disconnect switch 36A.

This system of surge suppressor units 20 provides power factorcorrection (PFC) by optionally introducing power regulating products(e.g. capacitors 37) to help streamline the power current making theenergy more efficient.

Preferably, the surge suppressor unit 20 (FIG. 4) also includes one ormore appropriate sensors 38, which preferably include a current sensor.The sensor 38 connects to a control system 39 for detecting andmonitoring the sensor 38. The control system 39 may also include remote(web-based) diagnostic and reporting features such as that shown in thedata display 40 of FIG. 5. The data display 40 may be located remotefrom the various surge suppressor units 40 for monitoring by utilitypersonnel, such as through a computer terminal. The data display 40preferably shows information regarding faults (imbalances) that areproactively communicated and can be monitored from off-site locations.The data display 40 includes several display graphs 41, 42, 43 and 44which can display various types of data. This real time status reportingwould provide significant information and data including but not limitedto:

Voltage by phase

Amps by phase

Harmonics by phase

Oil/Coolant Temperature

Ground fault indicator (by phase and the severity of each occurrence).

The control system 39 may include alarms for every data point, whichalarms could be customizable so as to trigger utility response tomultiple remote locations. This is critical with grid level powersubstations that are often un-manned and/or in remote settings. Everydata point can be captured, stored, and maintained with data storagemeans within the control system 39 for historical tracking and referenceso as to allow for both historical trend analysis and specific searchcapability.

Focusing on voltage allows the invention to address each of the 5 CommonPower Issues discussed above. Transients are the brief voltage spikesthat occur regularly and may last only a few cycles. The inventivesystem would take the surplus voltage in the same waveform andelectromagnetically feed it back on itself with the same intensitythrough the transformers 31, 32 and 33. Even with a power analyzer onecould see that disturbances placed directly on line are completelymitigated.

Interruptions have many causes but the damage occurs in the briefmoments as a system loses power and motors which wind down turn intomini generators sending inappropriate voltages to connected loads. Thesystem of the invention would not prevent sustained power losses butwould prevent damage to loads by allowing a softer landing should anoutage occur due to the interaction of the transformers 31, 32 and 33and the resistor 35.

The invention will also reduce the harmful effects of voltageinstability like sags and swells or under/over-voltage at a grid level.The primary sides 31P, 32P and 33P of the transformers 31, 32 and 33 andtheir adjoining secondary sides 31S, 32S and 33S constantly stabilizethe voltage discrepancy. If there is a sustained swell, the excess poweris harmlessly drained off to the integrated resistor bank 35 that isseries wired on the secondary side of the system.

Waveform and frequency variations might best be described as noise onthe line from massive magnetic forces. These magnetic hits to the gridcan cause damage to generators, transformers, auto tapping devices, andconnected loads throughout. High frequency noise from hostile EMPschange the normal 60 Hz flow of electrons which may wreak havoc oninfrastructure. Depending on the severity or proximity to suchhostilities, damage could range from loss of end user electronic devicesto the overheating of the stators on utility generation plants or powertransformers. The surge suppressor units 20 of the present inventionwould act as a gatekeeper, suppressing any frequency above or below the60 Hz range. Damage to grid components could occur in an instant withoutthe system of the present invention but since it operates only on 60 Hzwaveforms it routs the inappropriate waveform to the integrated resistorbank 35 at the exact speed of the infraction. The invention, therefore,rectifies disturbances that are out of specification and harmonizeseveryday activity.

The system of the present invention provides significant advantages overprior surge suppressor devices. For example, the system of the presentinvention is designed for medium and high level voltages with a targetedapplication for grid system protection. Many prior surge suppressiondevices were designed for low voltage systems such as an industrial orresidential setting that are self-contained which have no “cascading”issues or additional sources of power to be concerned about. The presentinvention can accommodate the unique requirements of the power grid.

Further, each surge suppressor unit 20 does more than protect a singledevice. Rather each of the surge suppressor units 20 is wired inparallel at appropriate locations on the power grid to protect bothsides of grid level substations, power delivery systems, and generationplants. FIG. 3 provides an exemplary illustration of the extendedprotection provided by individual surge suppressor unit.

Further, the provision of a circuit breaker 36 and disconnects 36A inthe surge suppression units 20 allows the invention to be scaled tomedium and high voltage grid systems and facilitates hot tapping of eachunit 20 during installation or replacement. The surge suppressor unit 20also allows for the inclusion of Metal Oxide Varistors, which can beseries piped in as a secondary circuit, to add specific grid levelprotections for severe over-voltages.

More particularly, a surge suppressor device according to this designhas been tested at defined voltage levels under conditions representingan EMP of varying wavelength/shape and frequencies directly on linethrough injection. This testing was conducted with resistive andinductive loads using Mil-spec 188-125-1 and Mil-Std-2169 test standardsand equipment to represent grid level protection. Thousands of voltswere injected into a surge suppressor unit designed according to surgesuppressor unit 20 described above and a connected power system whereinthreat pulses were identified, clamped and drastically reduced everytime through multiple individual test events. FIGS. 6-9 illustrate testdata from such tests.

Generally as to an EMP such as a nuclear generated EMP, such pulses areconsidered to include three pulse components commonly designated as E1,E2 and E3. The E1 component is considered to be the quickest and caninduce high voltages in an electrical system. The E2 component is anintermediate pulse beginning at a short time after initiation of theelectromagnetic pulse and ending soon thereafter. This pulse isconsidered to be similar to a lightning strike but of a lessermagnitude. The E3 pulse component is longer and slower and is consideredmost similar to a solar flare. The E3 pulse component is the mosttroublesome component to deal whether it is generated by a nuclear EMPor a solar flare, and current technologies do not handle the E3 pulsecomponent and suitably protect grid systems.

In EMP testing of the present invention, the surge suppressor unit 20has shown to handle and protect against all three pulse components,namely E1, E2 and E3. The surge suppressor quickly clamps on EMP pulsethreats within millionths of a second and reduces the severity of thethreat to safe levels. For example, the unit mitigated the E1 pulseinstantaneously and eliminated the threat within 1.3 μsecs, the unitmitigated the E2 pulse instantaneously and returned the phases to“normal” within 0.002 seconds, and the unit also mitigated the E3 pulseinstantaneously and returned the phases to “normal” within 0.002seconds. The same device continued to operate throughout all tests andsuffered no damage such that it can be installed and performs throughmultiple EMP events.

FIG. 6 illustrates a graphical representation of the test results forthe three phases and their reaction to the injected E1 pulse which wasinjected under test conditions recreating such a pulse component. Thisgraph compares the kAmps detected in the system phases against the timemeasured in μseconds with pulse initiation at time 0. FIG. 6 shows theE1 pulse injection test from time −1.0 to 3.5 μsecs. The surgesuppressor unit was connected to a three phase circuit wherein thesystem under normal operating conditions was a 480 v operating systemwith 6000 watts of load. The test injected 20,000 volts at 1500 Amps tosimulate an E1 waveform. The height of the threat pulse 80 maxes out atnearly 1500 Amps (1.5 kA) on a single phase and lasts for over 1.9 microseconds. The threat pulse 80 is injected onto the operating system, andthe pulse is shown with a sudden spike with a diminishing tail. Thedarker Phase A load 81 and the lighter colored Phase B load 82 create animmediate dip to help correct the imbalance or resultant E1 spike on thePhase C load 83. The Phase C carried the wave from the injected load,but mitigates the impact by pushing the load back on to Phases A and B.Phases A, B and C of the surge suppressor unit have compensated for thethreat pulse by correcting the wave against itself or in other wordsbalances the pulse against the other two phases creating a real timecorrection that can be seen in the graphs. As a result, the surgesuppressor unit immediately mitigates the surge and begins reducing themagnitude and width within 0.1 μsec. The threat is kept to less than 500amps at its peak as is reduced to below 250 Amps within 0.2 microseconds(70% reduction in amplitude). By reducing the height(magnitude/amplitude) and the width (duration) by such a wide margin,the surge suppressor renders the E1 threat harmless to the gridcomponents. The threat is completely eliminated by 1.3 μseconds.

FIG. 7 shows the graphical results of the surge suppressor unitresponding to an injected E2 threat. The threat pulse is shown as graphline 90 wherein the threat pulse is injected onto Phase C shown by line91 at approximately 5 kV with a 6 kw load being present. The pulse isshown as a sudden spike with a diminishing tail. The Phase A load 92 andPhase B load 93 create an immediate dip to help correct the imbalance onthe Phase C load 91 which exhibits a spike. Phase C 91 is alreadymitigating the impact by pushing the load back onto Phase A 92 and PhaseB 93. Phase C 91 peaks at 109 Amps compared to the 260 Amp peak of thethreat 90. All three phases are corrected and back in phase within 0.002seconds from the initial threat being injected on the line. All threephases 91, 92 and 93 are in alignment prior to the threat 90 beinginjected at time 0. All three phases are back in phase very quickly fromthe initial E2 threat being injected on the line. Therefore, the surgesuppressor unit also can readily handle the E2 pulse component or apulse exhibiting similar characteristics.

The surge suppressor unit was also tested under an E3 pulse componentwhich is shown in FIGS. 8 and 9. FIG. 8 shows the graphical results withthe threat pulse 100 injected onto Phase C 101 at approximately 2 kVwith a 6 kw load. The threat pulse is clearly shown in FIG. 8 with asudden spike and corresponding waves. Due to the scale of the graph inFIG. 8, the reaction of the phases is not entirely clear. As such, FIG.9 is provided with the threat pulse 100 omitted so that the scale of thesystem phases can be increased for clarity. As seen in FIG. 9, Phase C101 has an immediate spike. However, the Phase A load 102 and the PhaseB load 103 create an immediate dip to help correct the imbalance on thePhase C load 101. Phase C already mitigates the impact of the threatpulse 100 by pushing the load back on to Phase A 102 and Phase B 103.Phase C 101 peaks at 109 Amps compared to the 1710 Amp peak of thethreat pulse 100. All three phases 101, 102, and 103 are corrected andback in phase within 0.002 seconds from the initial threat pulse 100being injected on the line. All three phases are in alignment prior tothe threat pulse 100 at time zero, and back in alignment within 0.002seconds, such that the surge suppressor can readily handle the E3 pulsecomponent.

As such, the inventive surge suppressor system can prevent the need toshed load in the presence of E3 activity or solar flare activity on thegrid by correcting the flattening of the AC waveform. By maintaining 3perfectly balanced phases where the vectors are 120 degrees out ofphase, the surge suppressor eliminates the need to reduce LPT loads toprevent overheating and damage from half cycle saturation.

Preferably, the surge suppressor unit never routes surplus energy fromthese electromagnetic forces to ground, and instead, said energy isthrown against the incoming surge at the speed of the infraction. Muchlike a mirror instantaneously rebounds a beam of light, the surgesuppressor system rebounds pulse threats to mitigate the inrush of powerregardless of the magnitude.

The surge suppressor system can be installed nearly anywhere within thepower distribution grid and still protect the entire portion of thecircuit. This means a surge suppressor unit could be installed midwaybetween the LPT and the next step down transformer which eliminates theneed for a new piece of equipment in an already crowded space at thepower source.

Although particular preferred embodiments of the invention have beendisclosed in detail for illustrative purposes, it will be recognizedthat variations or modifications of the disclosed apparatus, includingthe rearrangement of parts, lie within the scope of the presentinvention.

The invention claimed is:
 1. A surge suppression system of a powerdistribution system of a power grid which provides power to low-voltagepower consumers, comprising: at least one three phase system transformerof said power distribution system having a primary side which receivesthree phase power from a power source through a first set of powerdistribution lines, which each transmit a respective phase of said threephase power, and a secondary side, which supplies three phase powerdownstream through a second set of power distribution lines which eachtransmit a respective one of said phases of said three phase power, saidprimary and secondary sides including respective primary and secondaryside coils to transform said three phase power from a first voltage onsaid primary side to a second voltage on said secondary side differentfrom said first voltage, said system transformer stepping said firstvoltage up to or stepping said first voltage down from one of a mediumvoltage or a high voltage; and at least one surge suppressor unit whichis shunt-connected to said second set of power distribution linesbetween said secondary side of said system transformer and another threephase system transformer via respective direct electrical connections,said surge suppressor unit comprising a plurality of transformer bankswhich correct voltage surges resulting from harmonics in said threephase power, each of said plurality of transformer banks including (i) arespective primary coil which connects to and receives the respectivephase of three phase power carried by said second set of distributionlines at said second voltage and (ii) a respective secondary coil whichconnects in series together with a secondary coil of each other of saidplurality of transformer banks and has a resistor connected in seriestherewith to harmlessly drain energy due to harmonics in said threephase power, wherein said plurality of transformer banks transform saidthree phase power at said second voltage to three phase power at a thirdvoltage.
 2. The surge suppression system according to claim 1, whereinsaid surge suppressor unit is sized to the voltage class and kVAassociated with said second voltage.
 3. The surge suppression systemaccording to claim 1, wherein said primary coils of said surgesuppressor unit are connected to ground.
 4. The surge suppression systemaccording to claim 3, wherein said secondary coils of said first surgesuppressor unit are ungrounded.
 5. The surge suppression systemaccording to claim 1, wherein said first voltage is a high voltage andsaid second voltage is a medium voltage.
 6. The surge suppression systemaccording to claim 1, wherein said first set of power distribution linesincludes first, second, and third power distribution lines, and saidsecond set of power distribution lines includes fourth, fifth, and sixthpower distribution lines.
 7. The surge suppression system according toclaim 1, wherein said voltage surges are also due to at least one of (i)an electromagnetic pulse (“EMP”), (ii) a geomagnetic disturbance(“GMD”), (iii) a voltage swell, (iv) a voltage sag, (v) a phaseimbalance, and (vi) a line fault.
 8. The surge suppression systemaccording to claim 1, wherein each phase of said three phase power isassociated with harmonics content.
 9. The surge suppression systemaccording to claim 7, wherein said voltage surges are created by an EMPcomprising at least one of E1, E2, and E3 pulse components, and saidsurge suppressor units counterbalance any of said E1, E2, and E3 pulsecomponents of said electromagnetic pulse.
 10. The surge suppressionsystem according to claim 7, said voltage surges having voltagesexceeding normal operating levels by at least ten times.
 11. A surgesuppression system of a power distribution system of a power grid whichreceives three phase power from a power source, transmits said threephase power at high and medium voltages and converts and supplies saidthree phase power at a low voltage, comprising: a plurality of threephase system transformers of said power distribution system which eitherstep said power up to or step said power down from one of said mediumvoltage or said high voltage, each of said system transformers having aprimary side which receives three phase power from a power sourcethrough a first set of power distribution lines, which each transmit arespective phase of said three phase power, and a secondary side, whichsupplies three phase power downstream through a second set of powerdistribution lines which each transmit a respective one of said phasesof said three phase power, said primary and secondary sides includingrespective primary and secondary side coils to transform said threephase power from a primary side voltage on said primary side to asecondary side voltage on said secondary side different from saidprimary side voltage, said power distribution system further includingat least one step down transformer stepping said secondary side voltagesupplied by an upstream one of said system transformers down to said lowvoltage for use by low voltage power consumers; and a plurality of surgesuppressor units shunt-connected to said second set of powerdistribution lines between said secondary side of a respective systemtransformer and at least one other three phase system transformer viarespective direct electrical connections, each said surge suppressorunit comprising a plurality of transformer banks which correct voltagesurges resulting from harmonics in said three phase power through saidsecond set of power distribution lines, each of said plurality oftransformer banks including (i) a respective primary coil which connectsto and receives the respective phase of three phase power received fromsaid power distribution system and (ii) a respective secondary coilwhich connects in series together with a secondary coil of each other ofsaid plurality of transformer banks and has a resistor connected inseries therewith to harmlessly drain energy due to harmonics in saidthree phase power, wherein said plurality of transformer banks transformsaid three phase power from said secondary side voltage of said systemtransformers to three phase power at a third voltage.
 12. The surgesuppression system according to claim 11, wherein said surge suppressorunits are sized to the voltage class and kVA associated with saidsecondary side voltages of said respective system transformer to whichsaid surge suppressor units are connected.
 13. The surge suppressionsystem according to claim 11, wherein said primary coils of each of saidsurge suppressor units are connected to ground, and said secondary coilsof said surge suppressor units are ungrounded.
 14. The surge suppressionsystem according to claim 11, wherein said system transformers step saidthree phase power either up to or down from one of said medium or highvoltages which is greater than said low voltage.
 15. The surgesuppression system according to claim 11, wherein said primary sidevoltage on a first one of said system transformers is received from arespective power generator which generates said three phase power forsaid power grid.
 16. The surge suppression system according to claim 11,wherein said first set of power distribution lines includes first,second, and third power distribution lines, and said second set of powerdistribution lines includes fourth, fifth, and sixth power distributionlines.
 17. The surge suppression system according to claim 11, whereinsaid voltage surges are also due to at least one of (i) anelectromagnetic pulse (“EMP”), (ii) a geomagnetic disturbance (“GMD”),(iii) a voltage swell, (iv) a voltage sag, (v) a phase imbalance, and(vi) a line fault.
 18. The surge suppression system according to claim11, wherein each phase of said three phase power is associated withharmonics content.
 19. The surge suppression system according to claim17, wherein said voltage surges are created by an EMP comprising atleast one of E1, E2, and E3 pulse components, and said surge suppressorunits counterbalance any of said E1, E2, and E3 pulse components of saidelectromagnetic pulse.
 20. The surge suppression system according toclaim 17, said voltage surges having voltages exceeding normal operatinglevels by at least ten times.